Compartmentalized transport refrigeration systems of the prior art conventionally utilize a host refrigeration unit mounted on the nose of a truck or trailer, which serves a front compartment directly behind the nose wall, and one or more remote compartments containing remote refrigeration units. The remote compartments are usually arranged in series between the front compartment and the back wall of the truck or trailer. The remote refrigeration units disposed in the remote compartments each include an evaporator which is connected to hot gas, liquid and suction lines of the host refrigeration unit, via hot gas, liquid and suction lines associated with each remote unit.
In such prior art compartmentalized transport refrigeration systems, the front compartment served by the host refrigeration unit always serves the lowest temperature load, eg., if there is a frozen load, the front compartment must serve the frozen load. This limits the flexibility of the user in selecting the sequence in loading frozen and fresh loads, and if the compartments are of different sizes, the loads must be placed in the compartments according to the temperatures which the compartments can control, rather than matching the size of a load to the size of a compartment. Thus, it would be desirable, and it is an object of the invention, to be able to accommodate any temperature load in any compartment, and especially to provide such flexibility in transport refrigeration systems having first, second and third compartments to be respectively conditioned by a host refrigeration system and by first and second remote refrigeration units.